1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method, and more particularly relates to a technique to adjust color reproducibility of an observed image depending on a difference in viewing angle.
2. Description of the Related Art
In a case where an observation target is observed at different viewing angles, a color of the observation target can look different depending on the viewing angle. This is known as an area effect of colors, which is a phenomenon where brightness, saturation and the like of a color look different depending on a viewing angle expressed as a ratio of the size of the observation target to a distance to the observation target in observation. Here, the viewing angle is an angle at which a display of the observation target can be correctly viewed.
In a printed material, for example, a color perceived in an outputted printed material having a large size is higher in saturation and brightness than that in a printed material having a small size. Accordingly, even if printed materials are outputted in the same color (brightness and saturation), the colors in the printed materials different in size cannot be perceived as the same color.
To counter such a problem, Japanese Patent No. 3988355 describes a technique to correct brightness of an output image according to a magnification factor of the output image with respect to an input image. Also, Japanese Patent Laid-Open No. 2007-322850 describes a technique to correct brightness, color and the like of a displayed image according to a viewing angle for observation. Japanese Patent Laid-Open No. 2009-5097 describes adjustment of a color gamut of a display device based on a viewing angle in observation of an image displayed on the display device.
However, the techniques described above are essentially to merely adjust a color in accordance with only the viewing angle of the image to be observed. In other words, these techniques do not consider a difference in viewing angle between two or more observation targets. For this reason, colors of the two or more observation targets may not be observed as the same color.